What is transmitted in the physical layer?

The physical layer transmits bit streams.

Physical Layer

The physical layer (or physical layer, Physical Layer) is the lowest layer in the computer network OSI model.

Physical layer regulations:

Provides mechanical, electronic, functional and standardized specifications for the creation, maintenance, and teardown of physical links required to transmit data. characteristics. Simply put, the physical layer ensures that raw data can be transmitted over various physical media. Both LAN and WAN belong to layer 1 and 2.

The physical layer is the first layer of OSI. Although it is at the bottom, it is the foundation of the entire open system. The physical layer provides transmission media and interconnection equipment for data communication between devices, and provides a reliable environment for data transmission. If you want to remember this first layer in as few words as possible, it's "Signals and Medium."

The main problems to be solved by the physical layer:

(1) The physical layer should shield the physical equipment and transmission media as much as possible. Different communication methods will make the data The link layer does not feel these differences and only considers completing the protocols and services of this layer.

(2) Give its service users (data link layer) the ability to transmit and receive bit streams (generally serial and sequential transmission bit streams) on a physical transmission medium. For this purpose, physical The layer should address the establishment, maintenance, and release of physical connections.

(3) Uniquely identify data circuits between two adjacent systems.

Main functions of the physical layer:

Provide data transmission channels and transmit data for data-side devices.

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